Wildcarded public user identities (WIMPU's) are added to the 3rd generation partnership project (3GPP) internet protocol (IP) multimedia subsystem (IMS) standards in 3GPP release 8. Wildcarded public user identities are used to enable routing traffic to a destination that in fact is responsible for a range of end user addresses, like for example an internet protocol private branch exchange (IP-PBX). A wildcarded public user identity is implicitly registered when such an entity registers.
All public user identities (IMPU's) that match an implicitly registered wildcard, are handled according to the same service profile that is associated with that wildcard. For originating traffic that means the nodes involved in setting up the call, such as a proxy call session control function (P-CSCF) or a serving call session control function (S-CSCF), need to match the P-Preferred-Identity/P-Asserted-Identity received in for example a session initiation protocol (SIP) INVITE message with all the wildcarded IMPU's known in these nodes. If multiple nodes are involved this requires an extensive amount of processing to be performed by these nodes.